spaschal on DSK3GDR082PROD with CFR

Section 25.147

14 CFR Ch. I (1-1-19 Edition)

Section 25.147 Directional and lateral control.
(a) Directional control; general. It must
be possible, with the wings level, to
yaw into the operative engine and to
safely make a reasonably sudden
change in heading of up to 15 degrees in
the direction of the critical inoperative
engine. This must be shown at 1.3 VSR1
for heading changes up to 15 degrees
(except that the heading change at
which the rudder pedal force is 150
pounds need not be exceeded), and
with - 
(1) The critical engine inoperative
and its propeller in the minimum drag
position;
(2) The power required for level flight
at 1.3 VSR1, but not more than maximum continuous power;
(3) The most unfavorable center of
gravity;
(4) Landing gear retracted;
(5) Flaps in the approach position;
and
(6) Maximum landing weight.
(b) Directional control; airplanes with
four or more engines. Airplanes with
four or more engines must meet the requirements of paragraph (a) of this section except that - 
(1) The two critical engines must be
inoperative with their propellers (if applicable) in the minimum drag position;
(2) [Reserved]
(3) The flaps must be in the most favorable climb position.
(c) Lateral control; general. It must be
possible to make 20Section banked turns, with
and against the inoperative engine,
from steady flight at a speed equal to
1.3 VSR1, with - 
(1) The critical engine inoperative
and its propeller (if applicable) in the
minimum drag position;
(2) The remaining engines at maximum continuous power;
(3) The most unfavorable center of
gravity;
(4) Landing gear (i) retracted and (ii)
extended;
(5) Flaps in the most favorable climb
position; and
(6) Maximum takeoff weight.
(d) Lateral control; roll capability. With
the critical engine inoperative, roll response must allow normal maneuvers.
Lateral control must be sufficient, at

the speeds likely to be used with one
engine inoperative, to provide a roll
rate necessary for safety without excessive control forces or travel.
(e) Lateral control; airplanes with four
or more engines. Airplanes with four or
more engines must be able to make 20Section
banked turns, with and against the inoperative engines, from steady flight at
a speed equal to 1.3 VSR1, with maximum continuous power, and with the
airplane in the configuration prescribed by paragraph (b) of this section.
(f) Lateral control; all engines operating. With the engines operating, roll
response must allow normal maneuvers
(such as recovery from upsets produced
by gusts and the initiation of evasive
maneuvers). There must be enough excess lateral control in sideslips (up to
sideslip angles that might be required
in normal operation), to allow a limited amount of maneuvering and to
correct for gusts. Lateral control must
be enough at any speed up to VFC/MFC
to provide a peak roll rate necessary
for safety, without excessive control
forces or travel.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-42, 43 FR 2321, Jan. 16,
1978; Amdt. 25-72, 55 FR 29774, July 20, 1990;
Amdt. 25-108, 67 FR 70827, Nov. 26, 2002;
Amdt. 25-115, 69 FR 40527, July 2, 2004]

Section 25.149 Minimum control speed.
(a) In establishing the minimum control speeds required by this section, the
method used to simulate critical engine failure must represent the most
critical mode of powerplant failure
with respect to controllability expected in service.
(b) VMC is the calibrated airspeed at
which, when the critical engine is suddenly made inoperative, it is possible
to maintain control of the airplane
with that engine still inoperative and
maintain straight flight with an angle
of bank of not more than 5 degrees.
(c) VMC may not exceed 1.13 VSR
with - 
(1) Maximum available takeoff power
or thrust on the engines;
(2) The most unfavorable center of
gravity;
(3) The airplane trimmed for takeoff;
(4) The maximum sea level takeoff
weight (or any lesser weight necessary
to show VMC);

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